Device for sharpening cutlery



Sept. 18, 1951 J. F. R. KARLSTROM 2,567,941

DEVICEFOR SHARPENING CUTLERY Filed 001;.

lNVEN OR ORNEY -t he edge of the container.

Patented Sept. 18, 1951 UNITED STATES; PATENT OFFICE DEVICE FORSHARPENING CUTLERY Johan Fredrik Robert Karlstriim, Stockholm, Sweden,assignor to Aktiebolaget Elektrolux, Stockholm, Sweden, a corporation ofthe King-.

dom of Sweden Application October 17 1945, Serial No. 622,723 In SwedenOctober 24, 1944 11 Claims. (Cl. 51-241) This invention relates todomestic appliances, 7

and more particularly to devices for sharpening cutlery, such as knives,for example, and provisions for mounting devices of this type in workingposition.

In known devices for sharpening cutlery a grinding disc is providedwhich is intended to V grind opposite faces of the knife edge insuccession so that the knives have to be reversed a number of times inorder that the knife edge shall be uniformly ground on both faces andthat the sharpening shall be completed.

On the other hand other sharpening devices have been pro- .posed forgrinding both faces of the edge simultaneously but such devices are inthe main too complicated for domestic use.

The main object of this invention is to provide a sharpening devicewhich is suitable for domestic-use and which may be applied to adomestic as to organization and method, together with the.

above and other objects and advantages thereof,

will be better understood by reference to the following description.

According .to the present invention the device 3 for sharpening cutlery,such as knives, includes a- .grinding disc intended to be positivelyrotated relatively to the knife or the like to be ground and havingaround its periphery a deep groove which is acute angled at its base andis of fixed dimensions and is intended for the simultaneous grinding ofthe two faces of the knife edge.

The base of the groove of the grinding disc is formed with a fineclearance, which clearance may be filled with a material, such as paperor the like, which is innocuous to the knife edges The grinding disc maybe formed throughout of grinding material or the walls of the groove maybe provided with grinding material secured thereto.

In :a, preferred construction the grinding disc J or wheel is connectedwith a driving roller which is arranged to be rotated by frictionalcontact with a rotatable member. For example, the driving roller may bepressed against the edge .of a

rotatable container of a kitchen machine of known type. In such a, casea support for the grinding disc and driving roller may comprise aresilient mounting which due to its inherent resiliency retainsthe'driving roller pressed against The invention will be hereinaftermore-fully described with reference to several embodiments thereof whichby way of exampl are illustrated in the accompanying drawing, in which:

Fig. 1 shows in side elevation the upper portion of a food mixing orkitchen machine having a sharpening device embodying the inventionmounted thereon; v

Fig. 2 shows in plan view the same machine and sharpening device;

Fig. 3 shows the device in plan view on an enlarged scale with the.grinding wheel and the driving roller in section;

Fig. 4 shows a detail of the mounting of the stirrup in the frame of thekitchen machine;

Fig. 5 shows in front elevation the grinding wheel, with one halfremoved; .and

Fig. 6 shows another embodiment of the grinding wheel in section,alsowith one half removed.

Referring to Figs. 1. and 2, a rotatable container of aso-c-alledkitchen machine. of known type is designated by Ill. The machine framecarries a swingable arm II which is preferably moved into an inoperativeposition during grinding by being swung prior to grinding into theposition shown in Figs. 1 and 2. I

The grinding member of the sharpening device comprises a grinding wheell2 and a driving roller 13 which are mounted for rotation on a supportM. The grinding wheel l2 consists of two halves or discs l'5, I6, whichare held together by screw threads 11. The driving roller l3, which ispreferably made of rubber, may also be secured by threads l-8 to a boss19 of the disc [5 but, if desired, it may be fastened in any other way,for instance by being vulcanized thereon. Since the diameter of thegrinding wheel is larger than lying in planes extending. at right anglesto each other. One arm 20 formsajournal vor-spindle rotatablysupporting. the grinding member and the other arm 2| is utilized tomount th bracket or the stirrup on the machine frame. The grindingmember is held in position on the journal 20 by spring-rings 22 and 23.The grinding member cannot be released from the journal until the discIt has been unscrewed from the disc [5, thus making the spring-ring 2.3accessible.

The arm 2| of the bracket or stirrup is enveloped in a rubber sleevemember 24 which positions the stirrup securely in a correspondingaperture 25 in the machine frame. In the kitchen machine shown in Figs.1 and 2 an already existing aperture is utilized for this purpose, theaperture becoming available by removing a scraping member therefrom whenth grinding device is to be used. When the arm 2| with the rubber sleevemember 24 thereon has been forced into the aperture 25 with .the bracketor stirrup in the position shown in Figs. 1 and 2, the arm 2 is held inposition due to the rubber sleeve member 24 being compressed between thearm and the rim of the aperture and pressing resiliently against bothelements. The driving roller I3 mounted on the other end of the stirrupis thus pressed against the container edge. On account of the elasticityof the sleeve member 24, the supportis able to pivot slightly about thearm 2? even when the container edge may be slightly non-circular inshape. This mounting, however, provides sufficient friction to preventthe stirrup from becoming loosened from its position other than when theoperator intentionally releases it manually. The sleeve member 24 may besuitabl connected to the arm 2|, as by vulcanization thereto,rorexample.

If desired, the sleeve member 24 ma also form a bearing for the arm 2|,in which case it desirably may be formed of metal, synthetic resin orabout the arm '2' I.

The inherent resilient mounting for the bracket or support I4 may, ifdesired, be replaced by a spring controlled pivoting arrangement betweenthe arm .21 and the main portion of the stirrup.

in the embodiment shown in Fig. 6, the two discs |5 and I6 of thegrinding wheel are constructed with inlaid grinding material 21 of Car-'borundum or similar material. In the embodiment shown in Fig. 3,however, the grinding material consists of two annular-sha ed pieces 28of sandpaper or emery cloth. The grinding wheel's l5 and It arepreferably made of synthetic resin or similar material which in and ofitself may serve as a bearing element at 20. Preferably the material isof the self-lubricating type since it cannot be assumed that thisbearing will be lubricated.

Due to the fact that the grinding wheel, as shown in Fig. 1, is locatedexternallyof the outer face of the container, any powder-or th likeresulting from grinding will not fall into the contamer.

In grinding a knife or the like it is held b the handle and the edge ofthe knife blade is moved down into the acute angled groove 29 whichextends about the rotating rinding wheel and is so formed that the edgeof the knife is then ground on its two faces. Th extreme edge isprotected by the grinding material being covered at the base'o'f thegroove by rings 30 of paper or similar material.

In view of the foregoing it will now be understood an improved kitchenutility appliance has been provided comprising a base having a drivingmember for rotating an upright vessel In about a vertical axis. Thebracket in having spaced apart ends 20 and 2| is disposed so that thedriven roller l3 and rotatable element l5 connected thereto are carriedby the end portion 20. The end portion 2| is supported at a regionoutside the vessel ID by structure associated with the base of thekitchen appliance, the bracket l4 being movable about such region at thevicinity of the sleeve member 24.

When the driven roller I3 is moved into frictional'engagement with thevessel III while the latter is rotating, rotating movement is impartedto the rotatable element l5 about an axis at an angle with respect tothe vertical axis of rotation of the vessel I'll. As best seen in Fig.2, the driven roller f3 is adapted to be moved into frictionalengagement with an exterior surface of the vessel If} at the top openedge thereof to impart rotating movement to the element |5 connected tothe roller.

In the embodiment of the invention shown and described above the elementf5 forms a knife sharpening accessory comprising grinding disc structurewhich provides an annular groove having opposing faces containingabrasive material. The roller 3 and disc I5 are rotatably carried by thearm 20 which is substantially perpendicular to the arm 2"| The resilientsleeve member 24 is disposed about the arm 2| which is adaptedto fitsnugly in the recess of a part serving as a support. In this way aresilient mounting is provided for the bracket l4 so that, when theknife is pressed downwardly in the groove with the edge thereofextending horizontally, the frictional engagement between the vessel ordriving memher It! and roller I3 is increased. Further, the sleevemember 24 of elongated form is of such size and so positioned that theinner contact surface thereof with the arm 2| is longer than the outercontact surface thereof with the wall of the recess.

The disc structure I5 comprises a plurality of parts which provide arelatively deep groove. The opposing faces of the groove containabrasive material and form an acute angle of such size that, when aknife or other piece of cutlery is positioned with the knife edgedirected toward the bottom of the groove and such edge in its lengthwisedirection is closely adjacent to or in a plane substantialy normal tothe axis of rotation and at the apex of the groove, both sides of theknife edge are conveniently adapted tobe subjected to abrasive action bythe material at the opposing faces to effect sharpening of the knifeedge. As best seen in Fig. 6, the separating member 30 prevents theopposing faces from being brought into abutting relation and keeps theabrasive material at such faces from coming into intimate contact at theapex of the groove.

While specific embodiments of the invention have been shown anddescribed, it is to be understood thatthis has been done for the purposeof illustration only and that the scope of the invention is not to belimited thereby but is to be determined by the appended claims wheninterpreted as broadly as the prior art will permit What is claimed is:

1. A device for sharpening cutlery, such as knives, for example,comprising a rotatable driving member, a driven roller which is adaptedto frictionally cooperate with the driving member, grinding discstructure connected to the driven roller for rotation about its axis,said structure including a plurality of parts constructed to provide arelatively deep groove about the periphery thereof, the opposing facesof the groov containing abrasive material and forming an acute angle ofsuch size that, when a knife or other "piece'of cutlery is insertedtherebetween with the knifeedge directed toward 'the-.bottom;of theg'ro'ove-and such edge in its lengthwise direction isclosely adjacent toor in a plane substantially normal to said axis. at the apex-of thegroove, both-sides of the knife edge are. conveniently adapted to besubjected to abrasive actionby the material at the opposing sharpening'of the knife edge. 'aseparating membe r for said parts whichis formed and arranged to prevent the opposing faces from being broughtinto abutting relation and keep the abrasive material at such faces fromcoming into intimate contact at the apex of the groove, an element uponwhich the roller is rotatably mounted, and means for resilientlymounting the element so that, when a knife is pressed downwardly in thegroove with the edge thereof extending horizontally, the frictionalengagement between the driving member and the roller is increased.

2. A device as set forth in claim 1 in which the rotatable drivingmember comprises an upright open vessel and the driven roller is adaptedto frictionally engage the upper edge of the vessel, and said means forresiliently mounting the element being so constructed and arranged that,when a knife is pressed downwardly in the groove with the edge thereofextending horizontally, the frictional engagement between the vessel andthe roller is increased, the roller having its axis of rotationsubstantially perpendicular to a plane bisecting the groove and passingthrough the apex thereof.

3. A device as set forth in claim 1 in which said element comprises abracket having two spaced apart arms disposed in planes substantiallyperpendicular to one another, the roller and disc structure beingrotatably carried by one of the arms, and means for resiliently mountingthe other arm so that, when a knife is pressed downwardly in the groovewith the edge thereof extending horizontally, the frictional engagementbetween the driving member and the roller is increased.

4. A device for sharpening cutlery, such as a knife, for example,comprising a rotatable driving member, a driven roller which is adaptedto frictionally cooperate with the driving member, grinding discstructure connected to the driven roller constructed to provide anannular groove having opposing faces containing abrasive material, anelement upon which the roller is rotatably mounted, and means forresiliently mounting the element so that, when a knife is presseddownwardly in the groove with the edge thereof extending horizontally,the frictional engagement between the driving member and the roller isincreased.

5. A device as set forth in claim 4 in which the rotatable drivingmember comprises .an upright open vessel and the driven roller isadapted to frictionally engage the upper edge of the vessel, and saidmeans for resiliently mounting the element being so constructed andarranged that,

when a knife is pressed downwardly in the groove with the edge thereofextending horizontally, the frictional engagement between the vessel andthe roller is increased, the roller having its axis of rotationsubstantially perpendicular to a plane bisecting the groove and passingthrough the apex thereof.

6. A device as set forth in claim 4 in which said element comprises abracket having two tially perpendicular to one another; the roller facesto effect Q6 'anddisc structure being rotatablycarried by one of thearms,'and meansforresiliently mounting the other arm so that, when aknife is pressed downwardly'in the groove with the edge thereofextending horizontally, the frictional engagement between the drivingmember andtherroller is increased.

'7. A device for sharpening cutlery, such as a knife, for example,comprising a support, a rotatable driving member carried by the support,a driven roller which is adapted to frictionally cooperate with thedriving member, grinding disc structure connected to the driven rollerconstructed to provide an annular groove having opposing facescontaining abrasive material, a bracket having two spaced apart armsdisposed in planes substantially perpendicular to one an other, theroller and disc structure being rotatably carried by one of the arms, apart mounted on said support which is formed with a recess, and meansincluding a sleeve member disposed about the other arm which is adaptedto fit snugly in the recess for resiliently mounting the bracket sothat, when a knife is pressed downwardly in the groove with the edgethereof extending horizontally, the frictional engagement between saiddriving member and said roller is increased, the sleeve member beingelongated and having a longer contact surface with the other arm thanwith the wall of the recess.

8. A device for sharpening cutlery, such as a knife, for example,comprising a supporting base, a rotatable driving member carried by thebase, a driven roller which is adapted to frictionally cooperate withthe driving member, grinding disc structure connected to the drivenroller constructed to provide an annular groove having opposing facescontaining abrasive material, a bracket having two spaced apart armsdisposed in planes substantially perpendicular to one another, theroller and disc structure being rotatably carried by one of the arms, apart mounted on the base which is formed with a recess, and meansincluding a sleeve member disposed about the other arm which is adaptedto fit snugly in the recess for resiliently mounting the bracket sothat, when a knife is pressed downwardly in the groove with the edgethereof extending horizontally, the frictional engagement between thedriving member and the roller is increased.

9. A device as set forth in claim 8 in which the sleeve member is formedof material possessing sufficient resiliency to enable the roller to bebrought into good frictional engagement with the driving member.

10. A kitchen utility appliance comprising a base, a driving membercarried by the base comprising an upright vessel rotatable about avertical axis, a driven roller which is adapted to frictionallycooperate with the vessel, a rotatable element connected to the drivenroller, a bracket having spaced apart end portions, the roller andelement being rotatably carried by one of the end portions, and meansassociated with said base for supporting the other end portion of thebracket at a region outside the vessel and about which region saidbracket is movable, said bracket and supporting means being soconstructed and arranged that, when the driven roller is moved intofrictional engagement with the vessel while the latter is rotating,rotating movement is imparted to the rotatable element about an axis atan angle with respect to the vertical axis of rotation of the vessel.

mama

n. A kitchen utility appliance as set mm in mm m m which said bracketand. supporting means are so constructed and arranged that the tmven'roller is adapted to: be mnved into trict'ion'a'lz engagement with anexterior surface of 5 the vessel in i mpartrotating movement. to-- theelement cem'rected tq the when a FREDRIK ROBERT KARLSTROM.

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